In last two decades, optical communications technologies have achieved rapid development. In an optical communications system, information is modulated into light to form an optical signal, the optical signal is transmitted to a destination by using an optical fiber, and the information carried in the optical signal is demodulated after arrival at the destination. Optical communications has advantages of a high speed and low crosstalk, and therefore is a development direction of a fixed network in future.
Before a signal is modulated, a laser needs to generate light. The laser is a device that employs a stimulated emission theory to enable light in some stimulated substance to be amplified or emitted in an oscillating manner. According to an existing commercial tunable laser, laser power is output from one port. When multiple laser beams with a same frequency are required, an additional beam splitting structure is required at an output end, or multiple same lasers are required. It can be seen that an existing laser features low laser beam generation efficiency and relatively high costs.